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Commit df4e8d2c authored by J. Bruce Fields's avatar J. Bruce Fields Committed by Al Viro
Browse files

locks: implement delegations 



Implement NFSv4 delegations at the vfs level using the new FL_DELEG lock
type.

Note nfsd is the only delegation user and is only using read
delegations.  Warn on any attempt to set a write delegation for now.
We'll come back to that case later.

Acked-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 617588d5

fs/locks.c

+45 −10
Original line number Diff line number Diff line
@@ -1292,28 +1292,40 @@ static void time_out_leases(struct inode *inode) 
	}

}



static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)

{

	if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE))

		return false;

	return locks_conflict(breaker, lease);

}



/**

 *	__break_lease	-	revoke all outstanding leases on file

 *	@inode: the inode of the file to return

 *	@mode: the open mode (read or write)

 *	@mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:

 *	    break all leases

 *	@type: FL_LEASE: break leases and delegations; FL_DELEG: break

 *	    only delegations

 *

 *	break_lease (inlined for speed) has checked there already is at least

 *	some kind of lock (maybe a lease) on this file.  Leases are broken on

 *	a call to open() or truncate().  This function can sleep unless you

 *	specified %O_NONBLOCK to your open().

 */

int __break_lease(struct inode *inode, unsigned int mode)

int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)

{

	int error = 0;

	struct file_lock *new_fl, *flock;

	struct file_lock *fl;

	unsigned long break_time;

	int i_have_this_lease = 0;

	bool lease_conflict = false;

	int want_write = (mode & O_ACCMODE) != O_RDONLY;



	new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);

	if (IS_ERR(new_fl))

		return PTR_ERR(new_fl);

	new_fl->fl_flags = type;



	spin_lock(&inode->i_lock);
@@ -1323,12 +1335,15 @@ int __break_lease(struct inode *inode, unsigned int mode) 
	if ((flock == NULL) || !IS_LEASE(flock))

		goto out;



	if (!locks_conflict(flock, new_fl))

		goto out;



	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)

	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {

		if (leases_conflict(fl, new_fl)) {

			lease_conflict = true;

			if (fl->fl_owner == current->files)

				i_have_this_lease = 1;

		}

	}

	if (!lease_conflict)

		goto out;



	break_time = 0;

	if (lease_break_time > 0) {
@@ -1338,6 +1353,8 @@ int __break_lease(struct inode *inode, unsigned int mode) 
	}



	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {

		if (!leases_conflict(fl, new_fl))

			continue;

		if (want_write) {

			if (fl->fl_flags & FL_UNLOCK_PENDING)

				continue;
@@ -1379,7 +1396,7 @@ restart: 
		 */

		for (flock = inode->i_flock; flock && IS_LEASE(flock);

				flock = flock->fl_next) {

			if (locks_conflict(new_fl, flock))

			if (leases_conflict(new_fl, flock))

				goto restart;

		}

		error = 0;
@@ -1460,9 +1477,26 @@ static int generic_add_lease(struct file *filp, long arg, struct file_lock **flp 
	struct file_lock *fl, **before, **my_before = NULL, *lease;

	struct dentry *dentry = filp->f_path.dentry;

	struct inode *inode = dentry->d_inode;

	bool is_deleg = (*flp)->fl_flags & FL_DELEG;

	int error;



	lease = *flp;

	/*

	 * In the delegation case we need mutual exclusion with

	 * a number of operations that take the i_mutex.  We trylock

	 * because delegations are an optional optimization, and if

	 * there's some chance of a conflict--we'd rather not

	 * bother, maybe that's a sign this just isn't a good file to

	 * hand out a delegation on.

	 */

	if (is_deleg && !mutex_trylock(&inode->i_mutex))

		return -EAGAIN;



	if (is_deleg && arg == F_WRLCK) {

		/* Write delegations are not currently supported: */

		WARN_ON_ONCE(1);

		return -EINVAL;

	}



	error = -EAGAIN;

	if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
@@ -1514,9 +1548,10 @@ static int generic_add_lease(struct file *filp, long arg, struct file_lock **flp 
		goto out;



	locks_insert_lock(before, lease);

	return 0;



	error = 0;

out:

	if (is_deleg)

		mutex_unlock(&inode->i_mutex);

	return error;

}

include/linux/fs.h

+15 −3
Original line number Diff line number Diff line
@@ -1022,7 +1022,7 @@ extern int vfs_test_lock(struct file *, struct file_lock *); 
extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);

extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);

extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl);

extern int __break_lease(struct inode *inode, unsigned int flags);

extern int __break_lease(struct inode *inode, unsigned int flags, unsigned int type);

extern void lease_get_mtime(struct inode *, struct timespec *time);

extern int generic_setlease(struct file *, long, struct file_lock **);

extern int vfs_setlease(struct file *, long, struct file_lock **);
@@ -1131,7 +1131,7 @@ static inline int flock_lock_file_wait(struct file *filp, 
	return -ENOLCK;

}



static inline int __break_lease(struct inode *inode, unsigned int mode)

static inline int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)

{

	return 0;

}
@@ -1961,9 +1961,17 @@ static inline int locks_verify_truncate(struct inode *inode, 
static inline int break_lease(struct inode *inode, unsigned int mode)

{

	if (inode->i_flock)

		return __break_lease(inode, mode);

		return __break_lease(inode, mode, FL_LEASE);

	return 0;

}



static inline int break_deleg(struct inode *inode, unsigned int mode)

{

	if (inode->i_flock)

		return __break_lease(inode, mode, FL_DELEG);

	return 0;

}



#else /* !CONFIG_FILE_LOCKING */

static inline int locks_mandatory_locked(struct inode *inode)

{
@@ -2003,6 +2011,10 @@ static inline int break_lease(struct inode *inode, unsigned int mode) 
	return 0;

}



static inline int break_deleg(struct inode *inode, unsigned int mode)

{

	return 0;

}

#endif /* CONFIG_FILE_LOCKING */



/* fs/open.c */